Field of the Invention
The present invention relates to an image capturing apparatus suitable for producing, by image processing, multiple images corresponding to observable optical images observable when an object space is observed from mutually different pupil areas.
Description of the Related Art
Various image capturing apparatuses are proposed each of which simultaneously performs image capturing of an object space through mutually different pupils to acquire multiple images respectively corresponding to the pupils.
A pupil when image capturing is performed is a factor on which a depth of field and a viewpoint of an captured image depend, and therefore performing image capturing of an object space through mutually different pupils to acquire multiple captured images enables realizing various functions. For example, multiple captured images whose viewpoints (depending on the pupils) are mutually different provide parallax information, which makes it possible to provide three-dimensional information of the object space. Furthermore, performing a reconstruction process on multiple captured images whose viewpoints are mutually different enables refocus, which is a focus control after image capturing for acquiring these captured images, and a viewpoint change.
PCT International Application Publication No. WO2006/039486 and U.S. Pat. No. 7,962,033 disclose cameras including a lens array disposed between a main lens and an image sensor and constituted by multiple minute lenses whose arrangement pitch is larger than a pixel pitch of the image sensor; each camera acquires multiple viewpoint images (so-called a light field).
However, acquiring such multiple viewpoint images by one camera as disclosed in PCT International Application Publication No. WO2006/039486 and U.S. Pat. No. 7,962,033 requires an image sensor having an extremely large number of pixels. This is because the number of pixels required for information acquisition depends on a product of a resolution of each viewpoint image and the number of pupils (the number viewpoints). Such an image sensor having an extremely large number of pixels causes an increase in cost of the image sensor and an increase in image data volume transmitted from the image sensor or stored.
Even if the image sensor has a small number of pixels, multiple viewpoint images having a high resolution can be acquired by performing pixel-shifting super-resolution using multiple images acquired through image capturing with scanning of the object space or through continuous image capturing with minute shifting of the image sensor.
However, these image capturing method acquire temporally shifted images and thereby cannot provide correct information when performing image capturing of an object space including a moving object.